Should that be a 5cm lens? Anyway, the 50mm lens has a very tight f/stop and thus can be great for taking pictures of fish because the shutter speed is greater. That being said, it doesn't guarantee success. I took about 80 pictures yesterday and only liked about 15. Normally if I shoot 80 pictures, 75 are serious contenders for sharing. Here are the ones I liked of three subjects: Spock my Naso tang; the male Lyretail Anthias; and the Flame Angel. Spock - She has ...